It is well known that high fidelity audio reproduction systems and their loudspeakers have substantially improved in quality in recent years, yet they still suffer from persistent problems. Many of the problems are associated with component audio reproduction systems wherein differing power amplifiers may be utilized with a variety of differing loudspeakers and the different amplifiers and loudspeakers have distinct operating characteristics. For example, the present inventor's own U.S. Pat. No. 6,771,781 disclosed a “variable damping circuit for a loudspeaker” that significantly enhances audio reproduction.
In modern component audio reproduction systems, it is common for two or more loudspeakers to be secured within a common enclosure having a large speaker referred to as a “woofer” for low or bass frequencies and having a small speaker referred to as a “tweeter” for high or treble frequencies of an audio signal generated by the amplifier and transmitted to the loudspeakers. Some such speaker enclosures even have a separate mid-range speaker. For such multiple loudspeaker enclosures or “speaker boxes”, a special circuit referred to as a “cross-over network” or a “frequency dividing network” is typically utilized to filter desired low range frequencies to the woofers and high range frequencies to the tweeter, as is well known. It is also known to have such cross-over networks within the amplifier and to have bass and treble speakers within separate speaker boxes at varying locations within a user's listening room.
While such cross-over networks have substantially increased high fidelity reproduction of recorded music, it is also known that unacceptable distortion often results from such sound reproduction cross-over networks. For example and as disclosed in U.S. Pat. No. 4,597,100 that issued on Jun. 24, 1986 to Grodinsky, et al., a form of distortion referred to as “time displacement distortion” results from stored energy in many electrical components of audio circuits. An example of such distortion includes capacitors in audio reproduction circuits being unable to release stored energy rapidly. It is known that capacitors are utilized in frequency cross-over networks. Grodinsky et al. proposes use of frequency independent energy dissipation components and radio frequency chokes to suppress induced radio frequency distortion within a cross-over network.
U.S. Pat. No. 4,475,233 to Watkins shows another endeavor to improve the sound reproduction associated with cross-over networks through use of resistive damping of coils, capacitors and loudspeaker drive units to suppress loudspeaker ringing associated with cross-over networks. Similarly, in U.S. Pat. No. 5,132,052 to Brisson, an attempt to improve sound reproduction in an audio system is disclosed by use of a discrete capacitor coupled in parallel with one of the audio signal conductor lines. While all of such known attempts to improve audio reproduction have produced modest improvements, there is nonetheless a significant level of distortion within known audio systems.
Accordingly, there is a need for an improved audio system that enhances reproduction of sound.